United States, officially United States of America, abbreviations U.S. or U.S.A., byname America,
country of North America, a federal republic of 50 states. Besides the 48 contiguous states that occupy the middle latitudes of the continent, the United States includes the state of Alaska, at the northwestern extreme of North America, and the island state of Hawaii, in the mid-Pacific Ocean. The coterminous states are bounded on the north by Canada, on the east by the Atlantic Ocean, on the south by the Gulf of Mexico and Mexico, and on the west by the Pacific Ocean. The United States is the fourth largest country in the world in area (after Russia, Canada, and China). The national capital is Washington, which is coextensive with the District of Columbia, the federal capital region created in 1790.

The major characteristic of the United States is probably its great variety. Its physical environment ranges from the Arctic to the subtropical, from the moist rain forest to the arid desert, from the rugged mountain peak to the flat prairie. Although the total population of the United States is large by world standards, its overall population density is relatively low; the country embraces some of the world’s largest urban concentrations as well as some of the most extensive areas that are almost devoid of habitation.

The United States contains a highly diverse population. Unlike a country such as China that largely incorporated indigenous peoples, the United States has a diversity that to a great degree has come from an immense and sustained global immigration. Probably no other country has a wider range of racial, ethnic, and cultural types than does the United States. In addition to the presence of surviving Native Americans (including American Indians, Aleuts, and Eskimos) and the descendants of Africans taken as slaves to the New World, the national character has been enriched, tested, and constantly redefined by the tens of millions of immigrants who by and large have come to America hoping for greater social, political, and economic opportunities than they had in the places they left. (It should be noted that although the terms “America” and “Americans” are often used as synonyms for the United States and its citizens, respectively, they are also used in a broader sense for North, South, and Central America collectively and their citizens.)

The United States is the world’s greatest economic power, measured in terms of gross national product (GNP). The nation’s wealth is partly a reflection of its rich natural resources and its enormous agricultural output, but it owes more to the country’s highly developed industry. Despite its relative economic self-sufficiency in many areas, the United States is the most important single factor in world trade by virtue of the sheer size of its economy. Its exports and imports represent major proportions of the world total. The United States also impinges on the global economy as a source of and as a destination for investment capital. The country continues to sustain an economic life that is more diversified than any other on Earth, providing the majority of its people with one of the world’s highest standards of living.

The United States is relatively young by world standards, being barely more than 200 years old; it achieved its current size only in the mid-20th century. America was the first of the European colonies to separate successfully from its motherland, and it was the first nation to be established on the premise that sovereignty rests with its citizens and not with the government. In its first century and a half, the country was mainly preoccupied with its own territorial expansion and economic growth and with social debates that ultimately led to civil war and a healing period that is still not complete. In the 20th century the United States emerged as a world power, and since World War II it has been one of the preeminent powers. It has not accepted this mantle easily nor always carried it willingly; the principles and ideals of its founders have been tested by the pressures and exigencies of its dominant status. Although the United States still offers its residents opportunities for unparalleled personal advancement and wealth, the depletion of its resources, contamination of its environment, and continuing social and economic inequality that perpetuates areas of poverty and blight all threaten the fabric of the country.

The land

The two great sets of elements that mold the physical environment of the United States are, first, the geologic, which determines the main patterns of landforms, drainage, and mineral resources and influences soils to a lesser degree, and, second, the atmospheric, which dictates not only climate and weather but also in large part the distribution of soils, plants, and animals. Although these elements are not entirely independent of one another, each produces on a map patterns that are so profoundly different that essentially they remain two separate geographies. (Since this article covers only the coterminous United States, see also the articles Alaska and Hawaii.)

Relief

The centre of the coterminous United States is a great sprawling interior lowland, reaching from the ancient shield of central Canada on the north to the Gulf of Mexico on the south. To east and west this lowland rises, first gradually and then abruptly, to mountain ranges that divide it from the sea on both sides. The two mountain systems differ drastically. The Appalachian Mountains on the east are low, almost unbroken, and in the main set well back from the Atlantic. From New York to the Mexican border stretches the low Coastal Plain, which faces the ocean along a swampy, convoluted coast. The gently sloping surface of the plain extends out beneath the sea, where it forms the continental shelf, which, although submerged beneath shallow ocean water, is geologically identical to the Coastal Plain. Southward the plain grows wider, swinging westward in Georgia and Alabama to truncate the Appalachians along their southern extremity and separate the interior lowland from the Gulf.

West of the Central Lowland is the mighty Cordillera, part of a global mountain system that rings the Pacific Basin. The Cordillera encompasses fully one-third of the United States, with an internal variety commensurate with its size. At its eastern margin lie the Rocky Mountains, a high, diverse, and discontinuous chain that stretches all the way from New Mexico to the Canadian border. The Cordillera’s western edge is a Pacific coastal chain of rugged mountains and inland valleys, the whole rising spectacularly from the sea without benefit of a coastal plain. Pent between the Rockies and the Pacific chain is a vast intermontane complex of basins, plateaus, and isolated ranges so large and remarkable that they merit recognition as a region separate from the Cordillera itself.

These regions—the Interior Lowlands and their upland fringes, the Appalachian Mountain system, the Atlantic Plain, the Western Cordillera, and the Western Intermontane Region—are so various that they require further division into 24 major subregions, or provinces (see map).

1Excludes 5 nonvoting delegates from the District of Columbia, the U.S. Virgin Islands, American Samoa, the Northern Mariana Islands, and Guam and a nonvoting resident commissioner from Puerto Rico.

2Includes inland water area of 78,797 sq mi (204,083 sq km) and Great Lakes water area of 60,251 sq mi (156,049 sq km); excludes coastal water area of 42,225 sq mi (109,362 sq km) and territorial water area of 75,372 sq mi (195,213 sq km).

Official name

United States of America

Form of government

federal republic with two legislative houses (Senate [100]; House of Representatives [4351])

Table of contentsIntroductionThe landThe peopleEconomyGovernment and societyCultural lifeHistoryPresidents of the United StatesVice presidents of the United StatesFirst ladies of the United StatesState maps, flags, and sealsState nicknames and symbolsGovernors of U.S. states and territories

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